The proposed work seeks to understand the persisting association between socioeconomic status (SES) and morbidity and mortality in middle aged and older adults. It will examine the extent to which two psychosocial factors (social integration and health behaviors) are linked to SES and can explain SEs differentials in morbidity and mortality. The National Health and Nutrition Examination Surveys (NHANES) provide a unique opportunity to explore the determinants of SES variations in health status in a large, heterogeneous, nationally representative population. Secondary data analyses will utilize both cross-sectional morbidity data (of NHANESI, NHANESII and the Hispanic HANES) and the prospective morbidity and mortality data from the on-going follow-up of NHANESI participants. The size and scope of the population in the NHANES data will allow for careful analyses of the age patterning of SES differences in health status, as well as the assessment of sociocultural variations in the differential distribution and differential efficacy of psychosocial variables. The significance of this study must be assessed against the background of the extremely fragmentary evidence that is currently available about the causal dynamics that influence the SES gradient in morbidity and mortality in middle and late life.